Pneumatically actuated hydraulic circuit for presses



Oct. 31, 1950 R. J. HESS PNEUMATICALLY ACTUATED HYDRAULIC K) INVENTOR.

CIRCUIT FOR PRESSES Filed Jan. 31, 1947 Patented Oct. 31, 1950 PNEUMATICALLY ACTUATED HYDRAULIC CIRCUIT FOR PRESSES Relza J. Hess, Chicago, Ill., assignor to American Steel Foundries, Chicago, 111., a corporation of New Jersey Application January 31, 1947, Serial No. 725,601

3 Claims. 1

This invention relates to hydraulic presses and more particularly to a novel actuating circuit adapted for operation of small inexpensive hydraulic presses.

Throughout the hydraulic press industry, and

particularly in the plastic molding field, there has been a demand for a small, relatively inexpensive hydraulic press for the production of small pieces involving simple pressing techniques and comparatively low tonnage. To meet this demand there have been designed many small presses of the laboratory type and a number of small presses constructed according to conventional designs for standard large size presses. Both of these types of presses have proved inadequate inasmuch as the laboratory type press is inconvenientto handle and is generally not powered, and the small presses of conventional design are necessarily expensive per unit of capacity because of the hydraulic pumps and motors required.

Thus this particular size range of hydraulic presses has been reluctantly neglected by press manufacturers in favor of designs and sizes which have warranted a considerable investment on the part of the purchaser. The present invention relates to a small size inexpensive hydraulic press which is power actuated and is suitable to meet the requirements of the industry.

A general object of the invention is to provide a practical and inexpensive powered hydraulic press for the above-mentioned purposes.

Another object of the invention is to design a hydraulic press comprising a novel actuating system including a pneumatic intensifier or power device for developing hydraulic pressure on the pressure or working stroke of the press.

Still another object of the invention is to design a novel actuating circuit such as above described whereby the rapid advance stroke of the press ram to the work is effected by pneumatic displacement of the hydraulic fluid in the associated reservoir and the pressure or working stroke of the ram against the work is effected by a pneumatic intensifier or pressure device.

A further object of the invention is to charge or set the pneumatic intensifier in a circuit such as above described by hydraulic fluid pneumatically forced from the press reservoir into the intensifier which is preferably discharged or actuated by pneumatic fluid directed thereto from an associated shop line;

The foregoing and other objects and advantages of the invention will become apparent from a consideration of the following specification and pressure device generally designated 58.

the accompanying drawing, wherein the single figure is a flow diagram of a novel pneumatically operated hydraulic circuit embodying the invention, the hydraulic press and the pneumatic intensifier being diagrammatically shown in central vertical section.

Describing the invention in detail and referring to the drawing, it may be noted that the hydraulic motor generally designated 2 is illus trated in greatly reduced size for the purpose of convenience, said motor comprising a press ram 4 which is reciprocal within a complementary cylinder 5 in the press frame 8. The frame 8 is provided with an annular internal reservoir Ill containing a-zbody of hydraulic fluid l2 which is admitted to the lower end of the cylinder 6 through a port l4 and a valve generally designated 16.

The valve [6 comprises a body or casing 18 With a bore 20 containing a complementary stem or spindle 22 which is connected by a pin 24 to a seat 26 adapted to open and close a port 28 through the inner end of the body [8. The seat 26 is spring-pressed to its closed position by a spring '30 acting against the stem 22 which is actuated to open and close the seat 26 by a cap or plug 32 threaded into the body I8 asat 34 and operated by a handle 36 against the resistance of a spring 38. Thus it will be understood that by rotating the handle 36 the plug 32 is operable to urge the stem 22 and the seat26 inwardly to the open position thereof against the resistance of the spring 30. Upon rotating the handle 36 in the opposite direction the spring 30 is released to urge the stem 22 and the seat 26 to their closed position preventing flow of fluid from the port l4. The spring 38 is operable to develop friction on the threads at 34 to create frictional resistance to actuation of the lug 32.

The reservoir H3 is connected to a pneumatic line 46 which is connected to a three-way selector valve 42 having a connection to a pneumatic supply line 44, such as a shop air line, supplied with pneumatic pressure fluid from an associated source (not shown). The valve 42 is also connected to a discharge or relief line 46 and to an intensifier or high pressure line 48 for a purpose hereinafter described.

The reservoir I0 is connected to a hydraulic pipe or line 50 which communicates through a one-way check valve 52 with the top of a cylinder 54 in a casing 56 of a pneumatic intensifier or The casing 56 is provided with a depending wall or projection 60 containing the before-mentioned cylinder 54, and the casing 56 is formed at its lower extremity with a relatively large pneumatic cylinder 62 receiving a piston 64 which is connected to a small piston 66 reciprocal within the cylinder 54. Thus the pistons 64 and 66 move as a unit within their respective cylinders to develop pressure against the ram 4 on the pressure orworking stroke thereof after said ram has completed its rapid advance stroke, as herein after described. v

The cylinder 54 is also connected to an hy draulic line or pipe 58 which communicates through a one-way check valve 10 with a port 12 in the frame 8 communicating with the lower endof the cylinder 6. The line 58 carries hydraulic fluid under high pressure from the cylinder 54 and is thus designated the high pressure line of the system and comprises a gauge 14 to' indicate the hydraulic pressure therein.

The pneumatic intensifier 58 is actuated or discharged by pneumatic pressure fluid flowing from the line 48 through a conventional regulator generally designated it said regulator comprising a body or casing 18 with a spring bonnet r casing 80 secured theretoin any convenient manner. The body 18'. comprises a. pneumatic inlet passage 82 and a pneumatic outlet passage 84 communicating through a port 86 which is adapted to be opened and closed by a seat 88; This seat is connected by a stem 90 to a flexible diaphragm 92 which abuts the convex bottom surface of a spring plate 94 actuated by a spring 96 which is adjustable to regulate the pressure of the pneumatic fluid flowing from the outlet passage 85. A baille plate; 98 carrying a tube ifiii is provided to dampen pulsations of 'the compressed fluid with: in the passage 84- which would otherwise tend 7 pressure or working stroke.

to cause a hunting or oscillating ac'tiohof the I valve augmenting the. flow of air therethrough.

Thus it will beund'erstood that pneumatic pressure fluid flowing through the ir-ilet port 82 passes thrcughv the port 8'5 when the seat 88 is in its opeii position and flows into the outlet passtage 3% W'he'n ressure built up within the outlet' passage 84 reacts through the tube iiiil against the diaphragm- 92 to build up a pressure value of predetermined magnitude thereagaihst, the spring 95'is compressed by the diaphragm 92 which is connected to the stem 90 and is thus operable to close the seat 8'8) thereby preventing the further flow of fluid from the inlet passage 82 to the outlet passage 8'4 until the pressure value in the latter passage drops below the predetermined value at which the spring. 93 is operable to thrustthe diaphragm 92' and the stem 9h downwardly, thereby opening the seat 88 against the resistance of a small spring, 10'2' which is operable to urge the seat 88 to its closed position upon the release of upward movement of the stem S 5. I

In operation of the novel circuit bove described, the valve l5 is actuated to its'a'dvarice position by rotating tli'e'valve lei/ch36 clbc'kwise, thereby opening the seat 26 to acco'mmoe date flow oflfluidlfrom the reservoir Hlthrough the port I 4 into the bottom. of the. cylinder 6...

At this time. the valve" 52- isactuated. to its matic line 48 which is connected to the reservoir l0, thereby exerting pressure against the body I2 of hydraulic fluid therein. Thus the hydraulic fluid is urged into the bottom of the cylinder 6 and the ram A is urged on its rapid advance stroke to the work. When the ram engages the work the valve It, may be closed, whereupon the hydraulic fluid is forced through the line 50 and the one-way check valve 52 into the cylinder 54 urging the pistons 66 and 54 downwardly to their set or charged position. It may be noted that if desired the valve It may be retained in its open position until the pressure is built" up sufiiciently within the line 50 to set or'charge the intensifier 5-8 as above described, whereupon the valve [6 may be closed.

After the intensifier 58 has been set and the valve l6 has been closed, as above described, the selector valve 42 is actuated to direct pneumatic pressure fiuidfrom. the supply line 44; to the pneumatic line 48 and through. the regulator 36 into a lifie its, the pneumatic pressure within which is adjusted by regulation of the device it. The pneumatic pressure from the line we passes into the cylinder 62 to exert a predetermined pressure against the large piston 6 3, thereby ur'gingflthis pistohrahd'the associated piston 65' upwardly to force the hydraulic fluid within the cylinder 5e outwardly through the line 68' and the one-way check valve iii into the port 12 and thence into the bottom of the cylinder 6 to urge the ram 6 on its pressure or working stroke;

Preferably, the above-described circuit. is. so designed that each stroke or discharge 6f the intensifier 58 is operable to move the press ram 6 approximately a quarter of an" inch on its If a lon er? stroke isfdesired the intensifier may be recharged by actuating the selector valve 42 first to its advanceposition whereat pneumatic pressure fluid is directed through theline' 4'6 to urge hydraulic fluid from the reservoir H3 through the line 56" into the cylinder 54 to reset the intensifier 58, and-thenthe selectorf valve 42 is actuated to its high pressure position" directing pneumatic pressure flu id through' the line t8, the intensifler 76' and the line lMiinto the cylinder 52, thereby actuating or discharging the. intensifier This procedure may be repeated until the ram *4 has reached and maintains the desired pressure or-travel. To release the pressure, the selector valve 42- is actuated to its neutral position whereatthe pneumatic fluid therein is direted to the discharge line and" the valve I6 is then opened, thereby releasing the pressure in the bottom of the cylinder 6' and perrhittihg the ram 5- to dropon its return stroke.

, The valve Hi'is" then left in its open position rapid advance position wherein pneumatic fluid until the- 4 has again completed its rapid advance stroke on the next cycle of the press.

It is to beunderstood that" I do not wish to be limited by the exact embodiment of the devicesho'wii is merely by Way ofi1lustra:.

tion and notrhita-t ion as various and other forms -"of the device will, of course, beapparent theseskill I valve means? adapted inlthe'rapid advance pcsi- 1 tion' thereof to accommodate flow of fluid from ed in the art without 'd'ep'arting from the spirit of the invention -or thescope said reservoir to said cylinder means and adapted in the closed position of said valve means to positively cut off said flow, an intensifier device comprising spaced cylinders and engaged pistons reciprocal therein, one of said cylinders and associated piston having a greater cross sectional area than the other, an hydraulic connection between said reservoir and said other cylinder entirely independent of said valve means and comprising one-way check valve means accommodating flow of hydraulic fluid to said other cylinder, a connection between said other cylinder and said cylinder means entirely independent of said operating Valve means and comprising one-way check valve means accommodating flow of hydraulic fluid to said cylinder means, pneumatic valve means operable in the advance position thereof to exhaust said one cylinder and to deliver pneumatic fluid from an associated source to said reservoir for urging the fluid therefrom to said cylinder means in the rapid advance position of said operating valve means thereby urging said ram means on rapid advance stroke thereof and forcing fluid from the reservoir to said other cylinder, and for urging hydraulic fluid from the reservoir to the other cylinder in the closed position of said operating valve means, said pneumatic valve means being adapted in the high pressure position thereof to deliver pneumatic fluid from said source to said one cylinder, and an adjustable valve connected between the pneumatic valve means and said one cylinder for regulating the pressure of pneumatic fluid delivered to said one cylinder.

2. In an actuating circuit for an hydraulic motor comprising cylinder means and ram means reciprocal therein; the combination of a closed reservoir of hydraulic fluid, operating valve means adapted in the rapid advance position thereof to accommodate flow of fluid from said reservoir to said cylinder means and adapted in the high pressure position to cut off said flow, a pneumatic intensifier unit comprising an hydraulic pressure device having a constant connection entirely independent of said operating valve means to said reservoir and having another constant connection to said cylinder means independent of said operating valve means and the first-mentioned connection, said intensifier device comprising a pneumatic pressure device operatively connected to said hydraulic device for actuation thereof, and pneumatic valve means adapted in one position thereof to exhaust said pneumatic pressure device and to deliver pneumatic pressure fluid to said to said pneumatic pressure device, and adjusting valve means connected between the pneumatic valve means and the pneumatic device for regulating pressure of pneumatic fluid delivered to said pneumatic pressure device.

3. In an actuating circuit for an hydraulic motor comprising cylinder means and ram means reciprocal therein; the combination of a closed reservoir of hydraulic fluid, operating valve means connected to said reservoir and to said cylinder means for accommodating flow of fluid from said reservoir to said cylinder means in the rapid advance position of said valve means and adapted in the high pressure position thereof to cut off said flow, a pneumaticintensifier unit comprising an hydraulic pressure device having a connection to said reservoir entirely independent of said operating valve means, and having another connection to said cylinder means entirely independent of said operating valve means and the second-mentioned connection, said intensifier unit comprising a pneumatic pressure device operatively connected to said hydraulic device for actuation thereof,

pneumatic valve means adapted in one position thereof to exhaust the pneumatic pressure device and to deliver pneumatic pressure fluid to said reservoir for urging the hydraulic fluid therein to said hydraulic pressure device and also to said cylinder means in the rapid advance position of I said operating valve means and for urging hyreservoir for urging the hydraulic fluid theredraulic fluid from said reservoir to said hydraulic pressure device in the high pressure position of said operating valve means, said pneumatic valve means being adapted in another position to deliver pneumatic pressure fluid to said pneumatic pressure device, valve means for cutting off communication between said hydraulic device and said reservoir when pneumatic pressure fluid is delivered to said pneumatic pressure device, one-way check valve means in the connection between said hydraulic pressure device and said cylinder means for accommodating flow of hydraulic fluid to the latter, and means for adjusting pressure of pneumatic fluid delivered from said pneumatic valve means to said pneumatic pressure device.

RELZA J. HESS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 552,274 Cole Dec. 31, 1895 706,688 Reynders et a1. Aug. 12, 1902 1,249,736 Frink Dec. 11, 1917 1,903,887 Widener Apr. 18, 1933 2,165,095 Frechette July 4, 1939 2,198,049 Dinzl Apr. 23, 1940 2,208,451 Eaton July 16, 1940 2,403,912 Doll July 16, 1946 

